The present invention relates to an abnormality testing apparatus for engine system, and more particularly, to an abnormality testing apparatus that tests an abnormality of an engine system based on historical data of the running state of a vehicle engine.
A typical engine system has an abnormality testing apparatus for detecting an abnormality of the system or for identifying a malfunctioning part. To improve the accuracy of tests, a typical testing apparatuses determines an abnormality based on historical data of the running state of the corresponding engine.
Japanese Unexamined Patent Publication No. 11-148420 discloses an abnormality testing apparatus. The apparatus determines an abnormality of a thermostat, which controls the flow rate of coolant, based on historical data of the engine. Specifically, the apparatus has a warming-up counter for estimating the temperature of coolant based on historical data of the running state of an engine. The apparatus determines whether there is an abnormality in a thermostat based on the counter value of the warming-up counter, which will be referred to as warming-up counter value. If the coolant temperature is less than a referential level when a predetermined period has elapsed after the engine was started and the warming-up counter value is equal to or greater than a predetermined value, the apparatus determines that there is an abnormality in the thermostat. The warming-up counter value corresponds to a predicted coolant temperature, which is computed based on the actual state of the engine on the supposition that the thermostat is operating normally. Since the warming-up counter value is used for determining an abnormality, an abnormality is accurately determined.
If the detected temperature does not smoothly increase, the valve of the thermostat may be stuck at the open position. That is, even if the engine was started from a cold state, coolant may be circulating between the radiator and a coolant passage in the engine. The manner in which the coolant temperature increases is significantly affected by the actual running state of the engine. Thus, determining an abnormality of the thermostat based only on the coolant temperature after the predetermined period may result in an erroneous determination. Such erroneous determination is prevented by determining an abnormality based on whether the warming-up counter value is equal to or greater than the predetermined value. When it is determined that there is an abnormality, a malfunction indicator lamp (MIL) in the passenger compartment is lit for notifying the passengers of the abnormality.
However, the warming-up counter value is cleared when the engine is stopped, or when the ignition switch is turned off, even if a test is not completed. Therefore, the computation of the predicted coolant temperature, which is computed when the engine is restarted, must be started over again. This causes the following disadvantages.
When the engine is temporarily stopped soon after being started from a cold state and is restarted after a short period, the coolant is still warm from the preceding running. Therefore, an abnormality may not be determined through a test. Even if an abnormality is detected, it takes a relatively long time to determine the abnormality.
In an engine system that performs so-called economy running mode, an engine is automatically stopped and restarted when the ignition switch is on. When the engine is stopped during economy running mode, the warming-up counter is not manipulated. Also, during economy running mode, each running time and each stopping time of the engine can be significantly short, which pronounces the above disadvantages.
Accordingly, it is an objective of the present invention to provide an abnormality testing apparatus for vehicle that accurately tests an abnormality at an early state.
To achieve the foregoing and other objectives and in accordance with the purpose of the present invention, an apparatus for testing an abnormality of an engine system is provided. The apparatus includes means for manipulating a variable. The variable manipulating means computes a variable that relates to the engine system based on the state of an engine and manipulates the variable in accordance with the state of the engine. The apparatus performs at least one of the abnormality test and judgment whether a test condition is satisfied according to the variable. The variable manipulating means manipulates the variable in the state of the engine. The state includes a state in which the engine is not running.
The present invention may be embodied in another apparatus for testing an abnormality of an engine system. The apparatus includes means for manipulating a variable. The variable manipulating means computes a variable that relates to the engine system based on the state of an engine and manipulates the variable in accordance with the state of the engine. The apparatus performs at least one of the abnormality test and judgment whether a test condition is satisfied according to the variable. When the engine is started, the variable manipulating means manipulates the variable based on the value of the variable that was manipulated when the engine was stopped immediately before and on historical data that represents the state of the engine. The state includes a state in which the engine is not running.
The present invention may also be embodied in a method for testing an abnormality of an engine system. The method includes computing a variable that relates to the engine system based on the state of an engine, manipulating the variable in accordance with the state of the engine, wherein the state includes a state in which the engine is not running, and performing at least one of the abnormality test and judgment whether a test condition is satisfied according to the variable.
Further, the embodiment may be embodied in another method for testing an abnormality of an engine system. The method includes computing a variable that relates to the engine system based on the state of an engine, manipulating the variable when the engine is started based on the value of the variable that was manipulated when the engine was stopped immediately before and on historical data that represents the state of the engine, wherein the state includes a state in which the engine is not running, and performing at least one of the abnormality test and judgment whether a test condition is satisfied according to the variable.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.